Pressure-sensing control



J. s. MACHADO 3,326,089

PRESSURE-SENSING CONTROL June 20, 1967 Filed June 4, A3.965

United States Patent O 3,326,089 PRESSURE-SENSING CONTROL John S. Machado, Woburn, Mass., assigner to United Electric Controls Company, Watertown, Mass., a corporation of Massachusetts Filed June 4, 1965, Ser. No. 461,264 1 Claim. (Cl. 92-5) This invention relates to pressure-sensing controls and has for its principal objects to provide a control which will operate at a number of different pressure ranges; to provide a sensing control which will operate at both negative and positive pressures; to provide a sensing control which will withstand overpressures with-out damage; to provide a sensing control which is extremely compact; to provide a sensing control which is weatherproof; and to provide a sensing control which is comprised of relatively few operating parts and is easy to manufacture and maintain in operating condition.

As herein illustrated, the control comprises a charnber, a diaphragm dividing the chamber -into two parts, the part at one side of the diaphragm being in communication by way of a passage with the pressure to be sensed, means loading the diaphragm in a direction opposing movement thereof in response to a pressure change in the chamber at the one side, a guide in the part of the chamber at the opposite side of the diaphragm, a piston supported by the guide with one end in contact with the diaphragm, and a plunger supported in the chamber at the opposite side of the diaphragm Iwith one end opposite the other end of the piston and the other end protruding from the chamber, the piston being operative in response to movement of the diaphragm in opposition to the loading means to move the plunger. The plunger is movable through a limited distance for operating a switch and embodies means operative to take up movement of the piston in excess of the predetermined distance. Specifically, the aforesaid means comprises a sleeve, a part adjustably threaded into the end extending from the chamber int-o engagement with the switch, a second part supported in the other end opposite the piston, and a spring situated between the parts. The guide has an annular end which engages the diaphragm and the part at the other side of the diaphragm has an annular shoulder against which the diaphragm is held clamped by the annular end of the guide. The guide contains a central hole concentric with the annular end face, and the piston has a stem extending through the hole, a shoulder which limits its movement relative to the guide and a head of smaller diameter than the annular end of the'guide which has contact with the diaphrgam so that there is an annularspace between the guide and the piston within which is situated a fold of the diaphragm. The loading means is alternatively a compression spring in the part of the chamber at the one side of the diaphragm, loading the diaphragm in a direction opposing a negative pressure change in the chamber at the one side or a compression spring in the chamber at the other side of the diaphragm, loading the diaphragm in a direction opposing movement thereof in response to a positive pressure change in the chamber at the one side.

The invention will now be described in greater detail with reference to the accompanying drawings wherein:

FIG. 1 is an elevation of the pressure-sensing device provided Iwith a hood, the latter being broken away in part;

FIG. 2 is a vertical section taken diametrically at 2-2 of FIG. l, with some parts shown in elevation designed for negative pressure; and

FIG. 3 is a corresponding view designed for positive pressure.

Referring to the drawings, the control comprises two hollow parts 10 and 12 having at their adjacent ends coextensive ilanges 14 and 16 and providing axially aligned concentric chambers 18 and 20 at the remote ends of which are passages 22 and 24. The anges 14 and 16 are provided with a plurality of registering holes 26 and 28, the latter being threaded so as to receive clamping screw bolts 30. The part 10 has an annular shoulder 32 inwardly of the bolt holes 26 which lies in the plane of the base of the flange and the part 16 has a `shoulder 34 which lies inwardly of the bolt holes, but is axially spaced from the face of the flange. A part 36, correspending in diameter to the open end of the part 12, is seated therein against the `shoulder 34 and has an annular end face 38 which lies opposite the shoulder 32 and concentric thereto and provides, in conjunction with the shoulder 32, clamping means for clamping a flexible diaphragm 40 therebetween when the parts are bolted together so as to provide a seal between the chambers 18 and 20. The part 36 contains an axial hole 42 for supporting and guiding a piston comprising a head 44 of smaller diameter than the inside diameter of the part 36 which engages the diaphragm and a stem 46 which extends slidably through the hole 42. A shoulder 45 limits movement of the piston by engagement with the end of a guide.

The diaphragm 4t), as illustrated, has a fold f the-rein which extends into the annular space between the head 44 and the inside of the guide part 36.

A bushing 48 -is situated in the passage 24 at the end of the part 12 and slidably holds a plunger assembly 50, one end of which protrudes from the chamber and has adjustably mounted in it a threaded part 52 and the other end of which is opposite the stem 46 of the piston and has a yieldable pin 54 extending therefrom. The pin 54 is held distended from the assembly by a compression spring (not shown). The spring sets into an-axial bore and bears against the inner end of the pin 54.

A coiled compression spring 58 is mounted in the chamber 18 with its ends supported by guides 60 and 62 so that it applies pressure to the diaphragm 40 in a direction opposing movement of the diaphragm in response to a pressure change in the chamber 18 of a negative sense. The guides 60 an-d 62 have tapered portions 64 and `66 which enter the ends of the spring. The guide 60 rests on a shoulder 68 concentric with the passage 22. The guide 62 has a flat face 70 which bears against the portion of the diaphragm opposite the head 44 of the piston and an annular axially projecting rim or rib 72 which projects into the fold f of the diaphragm.

The pressure-sensing device is adapted by a change in pressure to actuate a switch S fastened by screw bolts 74 to a post 76 formed integral with the part 12, which holds the switch with its actuator 78 in alignment with the end of the adjustable part 52. Electric conductor wires 80 are secured by suitable means to binding posts 82 on the switch and are led down one side of the post 76 to the ange 16 and then outwardly at right angles thereto. A screw clamp 84 provides for holding the conductor in place an-d a hood 86 is applied over the part 12 so as to enclose the switch and conductors, the lower edge of the hood resting on a shoulder 90 of the part 12.

In operation pressure to be sensed is connected by suitable means to the passage 22 leading to the chamber 18. The compression spring 58 in the chamber resists movement ofthe diaphragm in response to a change in pressure in the chamber 18 which is of a negative sense, that is it resists compression ydue to a negative pressure connected to the passage 22. A reduction in pressure forces the diaphragm downwardly, compressing the spring and lowering the piston 44 and the plunger assembly 50 and 3 this, in turn, actuates the switch S. The switch S in this instance is actuated by extension of its actuator.

The same pressure-sensing control with a very slight modification internally may be employed to sense positive pressure. Referring to FIG. 3, the device comprises the parts and 12 having coextensive flanges 14 and 16' which provide chambers 1.8 and 20. The flanges 14 and 16' contain registering holes 26 and 28', the latter being threaded to receive screw bolts 30 for fastening the parts together. The part 10" has an annular shoulder 32 inwardly of the circular bolt holes and the part 16 a shoulder 34 also inwardly of the circular bolt holes and axially spaced from the face of the ilange 16. The part 36' is seated in the part 12.' against the shoulder 34' and has an annular end face 38" which is opposite the shoulder 32 and provides means, in conjunction with the shoulder 32', to clamp a diaphragm 40 between the parts to seal the chamber 18 from the chamber 20. The part 36 has a hole 42 in axial alignment with the hole 24 and a piston comprising a head 44 and a stem 46' is supported in the part 36 with the head engaged with the diaphragm and the stem extending through the hole 42.

A bushing 48 is mounted in the hole 24 which slidably supports a plunger assembly 50", one end `of which projects from the chamber and has an adjustable part 52 threaded into it and the other end of which has projecting from it a pin 54. A coiled spring 56' situated in the part with one end bearing against the part 52 and the other end against the part S4 holds the pin extended with its projecting end opposite the stem of the piston. A coiled spring 58 is mounted in the chamber 20" in concentric relation to the plunger assembly so as to apply pressure to the diaphragm in a direction to oppose move- -rnent thereon in response to a pressure change in the chamber 18' which is positive in character. Spring guides 60 and 62 support the ends of the spring 58', the support 60 being provided by an inwardly projecting portion of the bushing 24. The spring guide 62 has an annular flange 66 which emcompasses the end of the spring, rests upon the end of the stem 46 and contains a central hole 67 through which the pin S4 is adapted to have contact with the stem of the piston.

A switch S' is fastened by bolts 74 to a post 76 integral with the part 12 with its actuator pin 78 opposite the part 52. Electric connectors (not shown) are attached to the binding posts 82 as described with respect to FIG. 2, and a hood 86 is applied to the part, the switch and the conductors.

In this form of the invention, a positive pressure applied through the passage 22 to the chamber 18 will move the diaphragm and hence the piston in a direction to compress the spring 58 and thus to force the piston upwardly against the pin 54 so as to move the plunger assem-bly upwardly and actuate the switch S. The switch in this instance is actuated by depression of its actuator.

It is evident from the foregoing that the two sensing devices are similar in construction except for the disposition of the springs 58 and 58 so that by a very simple assembly operation the valve may be suited for either purpose, to wit, by removing the spring 58 and guides 60 and 62 and inserting the spring S8 and guide 62 the device may be converted from sensing negative pressures to sensing positive pressures, and vice versa.

It should be understood that the present disclosure is for the purpose of illustration `only and that this invention includes all modifications and equivalents which fall within the scope of the appended claim.

I claim:

In a pressure-responsive device, a housing containing a chamber, a diaphragm dividing the chamber into two parts, the part at one side of the diaphragm containing a passage in communication with the pressure to be sensed, a guide supported in the part of the chamber at the opposite side of the diaphragm, said guide containing an opening concentric with the diaphragm, a piston supported by the guide with one end bearingagainst the diaphragm, spring means loading the piston and hence the diaphragm in a direction Aopposing movement thereof in response to a pressure change in the part of the chamber at the one side, said part of the chamber at the other side containing an opening concentric with the piston, a switch supported externally of the housing adjacent the opening in said other of the part of the chamber with the actuator confronting the opening, a plunger slidably supported in the opening with one end internally of the part of the chamber within which the piston is located and yieldably engaged with the piston, and the other end projecting exteriorly therefrom and in contact with the switchactuator, said plunger transmitting the motion of the piston directly to the actuator and comprising an elongated part, a spring pressed pin yieldably supported at its inner end, which pin engages the piston, and a nub threaded into the outer end, which nub has contact with the switch actuator, said spring being more resistant to displacement than the actuator, and said nub being adjustable to determine the operation of the switch in response to the movement of the piston.

References Cited UNITED STATES PATENTS 1,370,193 3/1921 Crocker 20G-83.5 1,938,327 12/1933 Green 20G-83.51 2,351,817 6/1944 Johnson 92-99 X 3,043,929 7/ 1962 Guthrie ZOO-83.51 3,119,910 1/1964 Meisenheimer et al. 200-83.51 3,216,332 11/1965 De Chambeau 92-5 3,217,309 11/1965 Parker 20D-83.5 3,2A4,191 4/ 1966 Grunau et al 92--59 X MARTIN P. SCHWADRON, Primary Examiner.

I. C. COHEN, Assistant Examiner. 

